test: rbd-mirror: compare positions using all fields

[trociny]

Comparing by only entry_tid may give false positives.

Signed-off-by: Mykola Golub mgolub@mirantis.com

[dillaman]

@trociny One of the tasks I want to get to next week is properly recording ownership within the journal tags to support failover/failback. For simple tests, I think the tag_tids will always align between two clients -- but for more complicated tests, I would expect them to diverge. For example, a peer that attaches to a remote journal after many exclusive locks (i.e. tag allocations) would result in a high tag tid on the remote side aligning with a small tag_tid on the local side.

[trociny]

@dillaman I guess what you describe is possible when comparing positions in different journals. But here I am comparing positions for two clients in the same journal. Shouldn't they always match exactly (object_number, tag_tid, entry_tid) if the positions are equal? They both pointing to the same event in the journal.

[dillaman]

Within the same journal, the tags should match. In that case, lgtm.